A well-known and useful method for generalised regression analysis when a linear covariate x is available only through some approximation z is to carry out more or less the usual analysis with E(x|z) substituted for x. Sometimes, but not always, the quantity var (x|z) should be used to allow for overdispersion introduced by this substitution. Th...

A well-known and useful method for generalised regression analysis when a linear covariate x is available only through some approximation z is to carry out more or less the usual analysis with E(x|z) substituted for x. Sometimes, but not always, the quantity var (x|z) should be used to allow for overdispersion introduced by this substitution. These quantities involve the distribution of true covariates x, and with some exceptions this requires assessment of that distribution through the distribution of observed values z. It is often desirable to take a nonparametric approach to this, which inherently involves a deconvolution that is difficult to carry our directly. However, if covariate errors are assumed to be multiplicative and log-normal, simple but accurate approximations are available for the quantities E(x-super-k|z) (k = 1, 2, …). In particular, the approximations depend only on the first two derivatives of the logarithm of the density of z at the point under consideration and the coefficient of variation of z|x. The methods will thus be most useful in large-scale observational studies where the distribution of z can be assessed well enough in an essentially nonparametric manner to approximate adequately those derivatives. We consider both the classical and Berkson error models. This approach is applied to radiation dose estimates for atomic-bomb survivors. Copyright 2004, Oxford University Press. Minimize

The quality factor, Q ( L ), used to be the universal weighting factor to account for radiation quality, until—in its 1991 Recommendations—the ICRP established a dichotomy between ‘computable’ and ‘measurable’ quantities. The new concept of the radiation weighting factor, w R , was introduced for use with the ‘computable’ quantities, such as ...

The quality factor, Q ( L ), used to be the universal weighting factor to account for radiation quality, until—in its 1991 Recommendations—the ICRP established a dichotomy between ‘computable’ and ‘measurable’ quantities. The new concept of the radiation weighting factor, w R , was introduced for use with the ‘computable’ quantities, such as the effective dose, E . At the same time, the application of Q ( L ) was restricted to ‘measurable’ quantities, such as the operational quantities ambient dose equivalent or personal dose equivalent. The result has been a dual system of incoherent dosimetric quantities. The most conspicuous inconsistency resulted for neutrons, for which the new concept of w R had been primarily designed. While its definition requires an accounting for the gamma rays produced by neutron capture in the human body, this effect is not adequately reflected in the numerical values of w R , which are now suitable for mice, but are—at energies of the incident neutrons below 1 MeV—conspicuously too large for man. A recent Report 92 to ICRP has developed a proposal to correct the current imbalance and to define a linkage between the concepts Q ( L ) and w R . The proposal is here considered within a broader assessment of the rationale that led to the current dual system of dosimetric quantities. Minimize

The objective of this study is to provide a set of proximity functions for electrons from 100 eV to 10 MeV. Numerical results of differential proximity functions are given graphically. The complete data set is available electronically upon request from the authors. The results can serve as a convenient database for anyone performing microdosimet...

The objective of this study is to provide a set of proximity functions for electrons from 100 eV to 10 MeV. Numerical results of differential proximity functions are given graphically. The complete data set is available electronically upon request from the authors. The results can serve as a convenient database for anyone performing microdosimetric calculations in radiation fields of electrons. For mixed fields of electrons, the proximity functions can easily be derived from the proximity functions of monoenergetic electrons presented here. Minimize

The objective of this study is to provide a set of proximity functions for electrons from 100 eV to 10 MeV. Numerical results of differential proximity functions are given graphically. The complete data set is available electronically upon request from the authors. The results can serve as a convenient database for anyone performing microdosimet...

The objective of this study is to provide a set of proximity functions for electrons from 100 eV to 10 MeV. Numerical results of differential proximity functions are given graphically. The complete data set is available electronically upon request from the authors. The results can serve as a convenient database for anyone performing microdosimetric calculations in radiation fields of electrons. For mixed fields of electrons, the proximity functions can easily be derived from the proximity functions of monoenergetic electrons presented here. Minimize

Conventional X rays, i.e. X rays generating voltage between roughly 150 and 300 kV, are used in many radio-diagnostic procedures and also in radiobiological experiments. They release less energetic and, therefore, more densely ionising electrons than the high-energy gamma rays from 60Co or from the A bombs. Accordingly, they are considered to be...

Conventional X rays, i.e. X rays generating voltage between roughly 150 and 300 kV, are used in many radio-diagnostic procedures and also in radiobiological experiments. They release less energetic and, therefore, more densely ionising electrons than the high-energy gamma rays from 60Co or from the A bombs. Accordingly, they are considered to be somewhat more effective, especially at low doses. Various radiobiological studies, especially studies on chromosome aberrations have confirmed this assumption, but epidemiological investigations, e.g. the comparison of the excess relative risk for mammary cancer in the X-ray exposed patients and in the gamma-ray exposed A bomb survivors, have not demonstrated a similar difference. In view of the missing epidemiological evidence and largely for the reasons of practicality in radiation protection, the ICRP has recommended the radiation weighting factor unity equally for all photon radiations. However, in the discussion preceding the 2005 Recommendations of the ICRP, the issue remains controversial. In a recent paper, Harder et al . argue--with reference to an assessment by the German Radiation Protection Commission (SSK)--that the use of the same weighting factor for different photon energies can be justified more directly. For high-energy incident photons, they present the degraded photon spectra at different depths in a phantom, and they conclude that much of the difference between high-energy gamma rays and conventional X rays disappears in a large phantom. The present assessment, which is more direct, compares the spectra of electrons released (through pair production, Compton effect and photo effect) in a small and in a very large receptor for the incident photons of 150 keV, 1 MeV and 6 MeV. For the 1 Mev and 6 MeV photons, there is a substantial shift towards smaller electron energies in the large receptor, but the electron spectra remain much harder than those from the 150 keV incident photons. Furthermore, it is seen--in agreement with earlier conclusions by Straume--that for the broad gamma-ray spectrum from the A bombs there is no shift at all to lower energies within the body, but rather some degree of hardening of the radiation. The assumption that distinct differences between high-energy gamma rays and conventional X rays are restricted to small samples must, thus, be rejected. The attribution of the same effective quality factor or radiation weighting factor to all photon energies remains, therefore, an issue that is based on the considerations beyond dosimetry. Minimize

Conventional X rays, i.e. X rays generating voltage between roughly 150 and 300 kV, are used in many radio-diagnostic procedures and also in radiobiological experiments. They release less energetic and, therefore, more densely ionising electrons than the high-energy gamma rays from 60Co or from the A bombs. Accordingly, they are considered to be...

Conventional X rays, i.e. X rays generating voltage between roughly 150 and 300 kV, are used in many radio-diagnostic procedures and also in radiobiological experiments. They release less energetic and, therefore, more densely ionising electrons than the high-energy gamma rays from 60Co or from the A bombs. Accordingly, they are considered to be somewhat more effective, especially at low doses. Various radiobiological studies, especially studies on chromosome aberrations have confirmed this assumption, but epidemiological investigations, e.g. the comparison of the excess relative risk for mammary cancer in the X-ray exposed patients and in the gamma-ray exposed A bomb survivors, have not demonstrated a similar difference. In view of the missing epidemiological evidence and largely for the reasons of practicality in radiation protection, the ICRP has recommended the radiation weighting factor unity equally for all photon radiations. However, in the discussion preceding the 2005 Recommendations of the ICRP, the issue remains controversial. In a recent paper, Harder et al . argue—with reference to an assessment by the German Radiation Protection Commission (SSK)—that the use of the same weighting factor for different photon energies can be justified more directly. For high-energy incident photons, they present the degraded photon spectra at different depths in a phantom, and they conclude that much of the difference between high-energy gamma rays and conventional X rays disappears in a large phantom. The present assessment, which is more direct, compares the spectra of electrons released (through pair production, Compton effect and photo effect) in a small and in a very large receptor for the incident photons of 150 keV, 1 MeV and 6 MeV. For the 1 Mev and 6 MeV photons, there is a substantial shift towards smaller electron energies in the large receptor, but the electron spectra remain much harder than those from the 150 keV incident photons. Furthermore, it is seen—in agreement with earlier conclusions by Straume—that for the broad gamma-ray spectrum from the A bombs there is no shift at all to lower energies within the body, but rather some degree of hardening of the radiation. The assumption that distinct differences between high-energy gamma rays and conventional X rays are restricted to small samples must, thus, be rejected. The attribution of the same effective quality factor or radiation weighting factor to all photon energies remains, therefore, an issue that is based on the considerations beyond dosimetry. Minimize